Dont set back button if leftButton is decalred dynamically (#3630)

lib/android/app/src/main/java/com/reactnativenavigation/parse/TopBarButtons.java

     @Nullable public ArrayList<Button> right;
 
     void mergeWith(TopBarButtons other) {
-        if (other.left != null) left = other.left;
+        if (other.left != null) left = mergeLeftButton(other.left);
         if (other.right != null) right = other.right;
         back.mergeWith(other.back);
     }
 
+    private ArrayList<Button> mergeLeftButton(ArrayList<Button> other) {
+        if (!other.isEmpty() && !CollectionUtils.isNullOrEmpty(left)) {
+            Button otherLeft = other.get(0);
+            if (otherLeft.id == null) {
+                left.get(0).mergeWith(otherLeft);
+                return left;
+            }
+        }
+        return other;
+    }
+
     void mergeWithDefault(TopBarButtons defaultOptions) {
         if (left == null) {
             left = defaultOptions.left;
         }
         back.mergeWithDefault(defaultOptions.back);
     }
+
+    public boolean hasLeftButtons() {
+        return !CollectionUtils.isNullOrEmpty(left) && left.get(0).id != null;
+    }
 }

lib/android/app/src/main/java/com/reactnativenavigation/parse/params/Button.java

 import java.util.ArrayList;
 
 public class Button {
-    public String id;
+    @Nullable public String id;
     public Text text = new NullText();
     public Bool enabled = new NullBool();
     public Bool disableIconTint = new NullBool();
         }
     }
 
+    public void mergeWith(Button other) {
+        if (other.text.hasValue()) text = other.text;
+        if (other.enabled.hasValue()) enabled = other.enabled;
+        if (other.disableIconTint.hasValue()) disableIconTint = other.disableIconTint;
+        if (other.color.hasValue()) color = other.color;
+        if (other.disabledColor.hasValue()) disabledColor = other.disabledColor;
+        if (other.fontSize.hasValue()) fontSize = other.fontSize;
+        if (other.fontFamily != null) fontFamily = other.fontFamily;
+        if (other.fontWeight.hasValue()) fontWeight = other.fontWeight;
+        if (other.testId.hasValue()) testId = other.testId;
+        if (other.component.hasValue()) component = other.component;
+        if (other.showAsAction.hasValue()) showAsAction = other.showAsAction;
+        if (other.icon.hasValue()) icon = other.icon;
+    }
+
     public void mergeWithDefault(Button defaultOptions) {
         if (!text.hasValue()) text = defaultOptions.text;
         if (!enabled.hasValue()) enabled = defaultOptions.enabled;

lib/android/app/src/main/java/com/reactnativenavigation/presentation/StackOptionsPresenter.java

     private void applyButtons(TopBarButtons buttons) {
         topBar.setLeftButtons(buttons.left);
         topBar.setRightButtons(buttons.right);
-        if (buttons.back.visible.isTrue()) topBar.setBackButton(buttons.back);
+        if (buttons.back.visible.isTrue() && !buttons.hasLeftButtons()) topBar.setBackButton(buttons.back);
     }
 
     private void applyTopTabsOptions(TopTabsOptions options) {